Voltage sag mitigation for a high frequency multistage power conversion system

A multistage power conversion scheme, capable of providing a regulated power supply despite disturbances in the source voltage or changes in the output load, is proposed. The high frequency power conversion system also provides compensation for acute voltage sags/swells and a faster transient response by employing appropriately controlled power electronics converters. Through the utilization of a bidirectional buck-boost DC-DC converter at the input of the three-phase DC-AC inverter, acute voltage sags in the AC or DC sources are compensated by supplying the necessary power from a battery pack through the boost action of DC-DC converter. In addition, the buck action of DC-DC converter provides a faster transient response during load withdrawals, wherein the excess energy from the system is extracted and stored in the battery pack. Simulation results are presented to demonstrate the effectiveness of the bidirectional buck-boost converter under both transient and acute voltage sag and swell conditions.